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[95.235.252.96]) by smtp.gmail.com with ESMTPSA id fy8sm7466618ejb.9.2020.08.31.00.41.09 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Mon, 31 Aug 2020 00:41:10 -0700 (PDT) From: To: "'Sibi Sankar'" , "'Viresh Kumar'" Cc: , , "'Sudeep Holla'" , "'Rafael J. Wysocki'" , "'Rob Herring'" , , , References: <20200821140026.19643-1-ansuelsmth@gmail.com> <20200824104053.kpjpwzl2iw3lpg2m@vireshk-i7> In-Reply-To: Subject: R: [RFC PATCH v3 0/2] Add Krait Cache Scaling support Date: Mon, 31 Aug 2020 09:41:08 +0200 Message-ID: <039d01d67f6a$188700d0$49950270$@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable X-Mailer: Microsoft Outlook 16.0 Content-Language: it Thread-Index: AQHE1KUT8lrzCHz2sVzN5qwVSE5wCwFurxwcAoW98xCpVYZpUA== Sender: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org > -----Messaggio originale----- > Da: sibis=3Dcodeaurora.org@mg.codeaurora.org > Per conto di Sibi Sankar > Inviato: luned=EC 31 agosto 2020 07:46 > A: Viresh Kumar > Cc: Ansuel Smith ; vincent.guittot@linaro.org; > saravanak@google.com; Sudeep Holla ; Rafael J. > Wysocki ; Rob Herring ; linux- > pm@vger.kernel.org; devicetree@vger.kernel.org; linux- > kernel@vger.kernel.org > Oggetto: Re: [RFC PATCH v3 0/2] Add Krait Cache Scaling support >=20 > On 2020-08-24 16:10, Viresh Kumar wrote: > > +Vincent/Saravana/Sibi > > > > On 21-08-20, 16:00, Ansuel Smith wrote: > >> This adds Krait Cache scaling support using the cpufreq notifier. > >> I have some doubt about where this should be actually placed (clk = or > >> cpufreq)? > >> Also the original idea was to create a dedicated cpufreq driver = (like > >> it's done in > >> the codeaurora qcom repo) by copying the cpufreq-dt driver and = adding > >> the cache > >> scaling logic but i still don't know what is better. Have a very > >> similar driver or > >> add a dedicated driver only for the cache using the cpufreq = notifier > >> and do the > >> scale on every freq transition. > >> Thanks to everyone who will review or answer these questions. > > > > Saravana was doing something with devfreq to solve such issues if I > > wasn't mistaken. > > > > Sibi ? >=20 > IIRC the final plan was to create a devfreq device > and devfreq-cpufreq based governor to scale them, this > way one can switch to a different governor if required. So in this case I should convert this patch to a devfreq driver-=20 Isn't overkill to use a governor for such a task? (3 range based on the cpufreq?) > (I don't see if ^^ applies well for l2 though). In the > interim until such a solution is acked on the list we > just scale the resources directly from the cpufreq In this case for this SoC we can't really scale the L2 freq with the cpu since we observed a bug and we need to switch back to the idle freq sometimes. Also this SoC use the generic cpufreq-dt driver and doesn't have a dedicated driver. So we must use a notifier. > driver. On SDM845/SC7180 SoCs, L3 is modeled as a > interconnect provider and is directly scaled from the > cpufreq-hw driver. >=20 > -- > Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, > a Linux Foundation Collaborative Project.